This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Viruses are the cause of many human diseases through out the world, and result in major financial losses to society. In the United States Influenza, a human pathogen, is responsible for an estimated total direct and indirect cost of $10 billion per year, and the costs of a serious future pandemic could cost hundreds of billions of dollars. Investigating virus assembly and entry will help researchers develop novel anti-viral targets and vaccines. The focus of this proposal is to use to electron microscope tomography to answer key questions about RNA virus lifecycle in vivo.